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                [Shoi2004]Mst 最小生成树                </h1>
                <p>时间限制：3s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：64MB</p>			</div>
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                                <h3>题目描述</h3><p><p><img border="0" alt="" src="../file/1937_0.jpg" /></p></p><hr/><h3>输入格式</h3><p><p>第一行为N、M，其中 表示顶点的数目， 表示边的数目。顶点的编号为1、2、3、&hellip;&hellip;、N-1、N。接下来的M行，每行三个整数Ui，Vi，Wi，表示顶点Ui与Vi之间有一条边，其权值为Wi。所有的边在输入中会且仅会出现一次。再接着N-1行，每行两个整数Xi、Yi，表示顶点Xi与Yi之间的边是T的一条边。</p></p><hr/><h3>输出格式</h3><p><p>输出最小权值</p></p><hr/><h3>样例输入</h3><pre>6 9
1 2 2
1 3 2
2 3 3
3 4 3
1 5 1
2 6 3
4 5 4
4 6 7
5 6 6
1 3
2 3
3 4
4 5
4 6

</pre><hr/><h3>样例输出</h3><pre>8

【样例说明】
	
边(4,6)的权由7修改为3，代价为4
边(1,2)的权由2修改为3，代价为1
边(1,5)的权由1修改为4，代价为3
所以总代价为4+1+3=8

修改方案不唯一。</pre><hr/><h3>提示</h3><p><p>&nbsp;1&lt;=n&lt;=50,1&lt;=m&lt;=800,1&lt;=wi&lt;=1000<br style="font-family: arial, verdana, helvetica, sans-serif !important; " />
n--&gt;点数..m--&gt;边数..wi---&gt;边权</p></p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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